From: Rob Seaman <>
Date: Sun, 16 Feb 2003 08:08:01 -0700 (MST)

> I've been reading a lot of NASA pages on the shuttle recently and was
> reminded once again that NASA seems to use "GMT" instead of "UTC" to
> label their timelines. Do any of you know why?

Because most of the planet - including highly technical communities -
implicitly assumes that GMT and UTC are interchangeable at the one
second (or one-tenth second) level.

Are the shadowy folks pushing the dystopian "no new leap seconds"
agenda going to claim that NASA has no standing on this issue?

> That brings up another question - has a leap second ever occurred
> during a NASA mission and did it have any effect on timing?

Doesn't it say something about the process being followed that the
answer to this and similar questions isn't completely clear? Doesn't
it say more that we also have no idea how terminating leap seconds and
disconnecting UTC from GMT will affect NASA (and ESA and Russion and
Chinese and commercial) space operations - and yet some small special
interest group is ready to vote a hasty change to a fundamental standard?

> Or is everything done in Mission Elapsed Time (MET) - one more example
> of a leapsecond-less timescale.

...and one more example of a community that may potentially incur huge
costs for remediation of, as yet, completely unquantified risks.

Rob Seaman
National Optical Astronomy Observatory
Received on Sun Feb 16 2003 - 07:08:11 PST

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